The more we learn about fungi, the less makes sense without them. Neither plant nor animal, they are found throughout the earth, the air and our bodies. They can be microscopic, yet also account for the largest organisms ever recorded. They enabled the first life on land, can survive unprotected in space and thrive amidst nuclear radiation. In fact, nearly all life relies in some way on fungi. These endlessly surprising organisms have no brain but can solve problems and manipulate animal behaviour with devastating precision. In giving us bread, alcohol and life-saving medicines, fungi have shaped human history, and their psychedelic properties have recently been shown to alleviate a number of mental illnesses.